> Comcast has been blocking port 80 (HTTP) for a while now, and they've> recently started blocking port 25 (SMTP) as well. IMNSHO, it's only a> matter of time before they start blocking all syn packets and charging> extra for ANY incoming connection, but for now you can do it with some> workarounds.

With cable's relatively limited upload speed, I can readily understand
blocking inbound port 80, where the traffic distribution is highly
skewed towards outbound packets. But why inbound port 25? It can't
be to prevent spam from infected PCs since they don't use it. Inbound
port 25 can only be used to receive mail and one could argue that
whether you receive your mail via SMTP (port 25), or POP or IMAP or
otherwise, the bits have to eventually flow in one way or another.

So, why block port 25? The only answer I can come up with is "just
for spite".

For that matter, the whole concept of "no servers" has always seemed
flawed to me: Technically, sshd and telnetd are servers. Does Comcast
really desire to have a policy of preventing one from contacting a
home machine when they are travelling?